Grinding and classifying apparatus



Jan. 18, 1944. A. c. HOBBlE 2,339,563

GRINDING AND CLASSIFYING APPARATUS I Filed April 16, 1941 WBRATORINVENTOR ANS/527C #05565 Patented Jan. 18, 1944 GRINDING AND CLASSIFYINQAPPARATUS Albert C. Hobbie, Moorestown, N. 1., assignor to InternationalPulverizing Corporation, Moorestown, N. J a corporation of New Jersey 7Application April 16, 1941, Serial N0. 388,872

2 Claims.

This invention relates to unitary fluid vortex grinding andclassifyingapparatus for the provision of materials in a finely divided form and ismore particularly concerned with an improvement in means wherein.finely-divided particles are separated from the driving fluid andcollected.

The present invention is primaril directed to an improvement in theapparatus described in United States Letters Patent 2,032,827. Theapparatus described in said patent comprises a gaseous vortex chamber,means to supply material to be ground to said chamber, and means inwhich gas and entrained fine particles from said vortex. chamber areseparated, the gas discharged, and the fine particles collected. As

shown in said patent, the vortex is created by a gas injected under arelatively high pressure into a circular planar zone, from variouspoints on the periphery of said zone, tangential to a theoretical circlewithin said zone. This produces an inwardly spiralling gaseous vortex insaid zone or chamber upon which is superimposed the jet action of thesaid high velocity Jets of gas introduced around the circular confiningwall of the vortex zone. As further shown in said patent, materials tobe ground may be introduced directly into the vortex chamber, preferablynear its periphery, through the top thereof by an injector type feeder.In carrying out the process described in said patent, certain materialshave evidenced a tendency to build up on 'the bottom of the vortexchamber and to bridge in the separating and collecting zone. As a resultof particle accretion on the confining walls of the separating zone andthe bottom of the vortex chamber, the efliciency of the grinding andclassifying action of the apparatus was reduced. Various types ofrapping and vibrating methods were applied to the separating zone withlittle or no success, dueto the localized vibration resulting from theiruse.

It is accordingly an object of the present invention to provide animprovement in the means for separating the gas and fine particleswhereiii by efiicient collection of the particles is obtained.

A further object of the invention is the eliminaa larly pointed out inthe claims, and illustrated in the annexed diagrammatic drawing; thefollowing description setting forth in detail certain means for carryingout the invention by way of illustration and constitute but several ofthe various ways in which the principle of the invention may be used.

In said annexed drawing:

The singl figure is a diagrammatic sectional elevation of one form ofapparatus embodying the invention. I

It has been established that fracturable material can be subdividedreadily by introducing such materials crushed to suitable fineness, e.g., 40 to 10 mesh, into a gaseous, inwardly spiralling, vortex createdwithin a generally circular planar axially-confined vortex chamber. Thedriving fluid is supplied continuously through a plurality of jets inthe circular confining wall of the chamber to maintain the vortex andthe fluid carrying fine particles of the solid, e. g., 1 to 10 micronsin size, is led from the vortex zone through a restricted opening into aco-axial gassolid separating zone. In this separating zone the vorticalmotion of'the gas stream continues and is utilized to throw out thesolid, the gas being discharged through a tube co-axial with said zonesand solid particles collecting in the bottom of the separating zone.

In my improvement in such apparatus, the hollow cylindrical collectionchamber is Joined, preferably integrally as by welding, to'the annularfloor of the vortex chamber to form a gastight joint. The'annular floor4 of the circular vortex zone is held between the Peripheral wall 2 ofsaid zone I and an annular supporting memher 8, a narrow spacing ring Ibeing used to prevent contact between the fioor 4 and the annularsupporting member 8. This arrangement permits the fioor 4 of the vortexzone to fiex and function as a diaphragm, since it is fixed at itsperiphery relative to the confining wall 2 of the vortex chamber I. Theother end of the collection chamber is mounted in a manner adapted topermit axial movement of the chamber and may be mounted to permit slightlateral move ment. Suitable means, such as a vibrator, are employed toimpart a reciprocating axial movement to said collection chamber whichalso causes the fiexure of the floor of the vortex zone.

Referring now to the drawing, the circular vortex chamber i is definedby a peripheral wall 2, a top plate 3, and an annular fioor or bottomplate 4. The peripheral wall 2 is pierced by a plurality of nozzles 5 toadmit a gas under pressure from a header 6. At the periphery of thebottom plate 4 is a spacing ring I resting upon an annular supportingmember I which carries, at least in part, the vortex chamber I.

From this annular supporting member I depend a plurality of verticalrods 9 which in turn carry an annular supporting member III for the pipeleading to a rotary discharge gate (not shown) and the lower end of thecollection chamber II. The circular wall I! of the collection chamber I2is fixed to the inner edge of the bottom plate 4. At its lower end, thewall IQ of the collection chamber I2 is secured to the inner edge ofannular plate H which is mounted at its periphery between resilientrings l5 and it. These rings l5 and ii are securely held in position bybolts l1 extending through the supporting member l0 and an annularretaining member It. A suitable vibrator I9 is mounted upon the wall itof the collection chamber II to impart a substantially axial motion tothe said wall and to cause flexing 01' the bottom plate 4 of the vortexchamber l. The entire mill assembly may be carried as on supportingbrackets 2 i Solid particles fed into the vortex chamber I through aninjector tube 22 are subdivided by the action of the fluid jets and theswirling gas stream carrying fine particles spirals inwardly toward thecenter of the vortex chamber. The spiralling gas stream moves down thewall I: of the collection chamber I 2 and vents upwardly through thecenter of the collector out through a co-axial tube 20.

In a mill of conventional construction, employing a bottom plate whichis not free to move as a diaphragm and in which the lower end 'of thecollection chamber is fixedly mounted, considerable trouble has beenexperienced in grinding materials such as titanium pigments and othermaterials having similar accretion characteristics. With theconstruction illustrated and described, it has been possible to operatethe apparatus over -periods of time exceeding a month whereas with andof the collector well be sufficient to support the internal pressure ofthe gas without deformation. In operating a mill with a vortex chamberthirty inches in diameter I have found that the bottom plate diaphragmand collector may be constructed of one-eighth inch mild steel plate.The resilient rings supporting the lower end of assesses the collectormay be of rubber or other plastic, being chosen to withstand thetemperature of the gaseous grinding medium.

While I have described a specific construction, it will be apparent fromthat construction that other means of securing the lower end of thecollector barrel may be utilized, and that the construction may bemodified in any desired man ner as long as the collector is free to movevertically and somewhat sideways and the bottom plate is fixed only atits periphery. The annular supporting member for the bottom of thecollector barrel may be of such size that it can be fixedly mounted atits periphery and still, by flexing action, permit vertical movement ofthe collector.

. I claim:

1. In a unitary grinding and classifying apparatus, the combination of agenerally circular, planar chamber axially confined by a top plate andan annular flexible bottom plate and havlnl jet openings in the circularconfining wall of said chamber through whicha gas under pressure can besupplied to create a gaseous inwardly spiralling vortex in said chamberwhich discharges therefrom through the opening in said annular bottomplate; means to supply material to be ground to said chamber; a hollow,generally cylindrical, collector fixed to said annular bottom plate nearthe inner concentric circle thereof and co-axial with said chamber; amounting for the other end of said collector adapted to permit axialmovement thereof; means to impart a reciprocating axial movement to saidcollector; and a gas discharge tube co-axial with said vortex chamberand said collector and extending through the top plate of said chamber.

2. In a unitary grinding and classifying apparatus, the combination of:a generally circular, planar chamber axially confined by a top plate andan annular flexible bottom plate and having jet openings in the circularconfining wall of said chamber through which a gas under pressure can besupplied to create a gaseous inwardly spiralling vortex in said chamberwhich discharges therefrom through the opening in said annular bottomplate; means to supply material to be ground to said chamber; a hollow,generally cylindrical, collector fixed to said annular bottom plate nearthe inner concentric circle thereof and co-axial with said chamber; amounting for the other end of said collector adapted to permit axialmovement thereof a vibrator for imparting a reciprocating axial movementto said collector; and a gas discharge tube co-axial with said vortexchamber and said collector and extending through the top plate of saidchamber.

ALBERT C. HOBBIE.

